Power tool



W. HALL POWER TOOL Jan. 26, 1937.

Filed June 26, 1935 2 Sheets-Sheet l www mw n mw Y v l i l IJ W. HALLPOWER TOOL .'.Im 26, 1937'.A

Filed June 26; v1935 2 Sheets-Sheet 2 Patented ".an. n 26, 937

UNI-TED STATES PATE-NT. OFFICE half to Calif.

J. Michael OMeara, Los Angeles,

Application Junev 26, 1935, Serial No. 28,528

20 Claims. -(Cl. 192-150) This invention relates to power driven devicesand relates more particularly to portable power driven tools such aspower wrenches, power drills,

power screw driversfetc. A 'general object of this invention is toprovide a power tool such as a power wrench having a simple, .practicaland effe tive automatic control clutch.

P wer wrenches, etc. are widely used in assembling plants for tighteningdown bolts, screws,

l0 nuts, etc. in fastening together and assembling machine parts. Powerwrenches commonly embody an electric motor governed by a switch underthe control of the operator and a releasable clutch between the motorshaft and the driven tool carrying spindle that releases when the screw,bolt, nut or the like is tightened down.

In assembling plants and the likethere is usually a great amount ofnoise and the operator of a power wrench does not always hear the soundproduced by the clutch teeth or clutch parts slipping one past'the otherfollowing the release of thepclutch of his tool, with the result thatthe clutch parts are allowedl to ratchet or slip past one another for aconsiderable period following the reljease of the clutch. This subjectsthe clutch parts to excessive Wear and consumes or wastes considerabletime. Further, care and skill are required in the operation oiga typicalpower wrench as the clutch must release against the weight of the wrenchand the inward pressure exerted on the tool by the operator andin theevent that the operator maintains an inward carrying spindle thatautomatically de-energizes" the motor when it releases upon tighteningdown of the nut r securing member, thus preventing excessive v ear ofthe clutch partsand conserv-I ing time.

Anotherobject of this invention isto provide an automatic circuitcontrolling or motor con--A trolling clutch embodied in a simple compactattachment lfor application to or vuse on 'a power wrench of the classnow inpgeneral use.

Another object of .this inventionis to` provide an attachment for apower tool that embodies an automatic clutch for controlling the motorofthe tool which-,attachment maybe easily ap- .'55 plied to a typicalpower wrench with but: little modification or alteration of the wrenchstructure. y

Another object of this invention is to 4provide a power tool that isoperable to tighten down a securing member to a definite degree oftightness 5 and therefore does not require that theI operator employgreat skill or care in its operation.

Another object of the invention is to provide a power tool such as apower wrench that embodies a clutch between the driving shaft and 10tool-carrying spindle that automatically releases when the nut or othersecuring member offers a definite resistance to'rotation, said releaseof the clutch being entirely irrespective of and independent of theinward pressure which the op- 15 erator may maintain on the tool.

Another object of this invention is to provide a power tool of thecharacter mentioned in which the torque controlled clutch controls thedriving motor operating to automatically de-energize 20 the motor whenit releases, under the torque resulting from the resistance o'iiered bya securing member which has been tightened down out which descriptionreference. is made to the accompanying drawings, in which:

Fig. 1 is a side elevation of one form of the present invention showingthe clutch and the adjacent parts in longitudinal cross section. Fig. 402 is a transverse detailed sectional view taken substantially asindicated by line 2--2 on Fig. 1. Fig. 3 is an enlarged fragmentarytransverse detailed sectional view taken as indicated by line 3-3 onFig. 1. Fig. 4 is a fragmentary side ele- 45 vation of a portion oi.'the wrench showing the clutch and the adjacent parts in longitudinalcross section withl the clutch in engagement and illustrating in adiagrammatic manner the electric circuit embodied in the tool. Fig. 5 isa side 50 elevation of a power tool with the attachment provided by thisinvention provided thereon illustrating the attachment and the adjacentparts of the tool in longitudinal cross section showing the clutch inthe released condition. Fig. 6 is a 55 transverse detailed sectionalview taken as indicated by line 6-6 on Fig. 5. Fig. Tis an enlargedfragmentary detailed sectional view taken as indicated by line 1 1 onFig. 5 and Fig. 8 is a fragmentary side elevation showing the clutch inthe engaged condition illustrating the attachment in longitudinal crosssection and diagrammatlcally illustrating the motor circuit.

The form of the present invention illustrated in Figs. 1 to 4,inclusive, of the drawings, in-

cludes, generally, a housing or body III containing a motor M foroperating a shaft II, a spindle I2 carrying a socket I3 or othersuitable means for engaging a securing member, anl automatic releasableclutch Il between the shaft I| and`the spindle I2, and a control I5 forthe motor M operatively associated with the clutch I4.

The body III is provided to encase the operating motor M and thereduction drive (not` shown) usually employed in power tools of thisclass. v'Ihe body I0 has a main part I6 for enclosing the motor M and areduced forward part I1 which may be considered as enclosing thereduction gearing (not shown). The present invention is not primarilyconcerned with the character or details of the motor M or the reductiongearing and these elements have been omitted from the present disclosureas they are well known to those skilled in the art. A suitable handle I8is provided at the rear or outer end of the body I0 and conductors I9and 20 carrying the current for energizing the motor M may enter thetool through the lower end portion of the handle I8. 'I'he shaft II,which is driven by the motor M through the reduction gearing (not shown)projects from the forward end of the reduced body portion I1. In thepreferred arrangement illustrated the shaft II is co-axial with the bodyI0. The spindle I2 is provided to carry the socket I3, al screw driverbit, or other device for nonrotatably engaging a. securing member to betightened by the tool or wrench. In the particular application of theinvention illustrated in the drawings the socket I3 is fixed to theouter or forward end portion of the spindle I2 to engage or receive anut, the head of a bolt, stud, screw, or the like. The spindle I2 isco-axial with the shaft II and body I0 projecting forwardly from a pointspaced from the forward end of the shaft II. The tool-carrying spindleI2 may'be cylindrical and may be of any suitable or desired length.

The clutch Il is provided to transmit rotation from the shaft II to thespindle I2 when the socket I3 is engaging a nut or securing member andthe operator is maintaining a suitable inward pressure on the wrench.The clutch I4 is an important feature of the invention as it is adaptedto automatically'release when the securing 4member has been tightened toa selected degree of tightness, its release causing actuation or openingof the control I5 and its release being entirely irrespective of theinward pressure maintained on the tool bythe operator.

In accordance with the invention the automatic clutch I4 includestwomembers 2| and 22 axially shiftable into and out of rotationtransmitting cooperation, one member being on the shaft |I and the othermember being shiftable on the spindle I2. In the particular form of theinvention illustrated in the drawings the clutch member 2| is fixed tothe shaft I I and the clutch member 22 is shiftably carried by thespindle I2. As sliown in the-drawings, the member 2| is integral withthe shaft II, it being understood that the member 2| may be a separablepart suitably xed or attached to the shaft. The clutch member 22 has asleeve portion 23 surrounding and shiftable on the spindle I2. member 22is splined or keyed to the spindle I2 to turn therewith and to beshiftable longitudinally thereon. In the simple form of the inventionillustrated in the drawings a key 24 cooperates with grooves or key-waysin the spindle I2 and member 22 to connect the member with the spindlefor rotation and relative longitudinal movement. A flange or head 25 isprovided on thc-inner end of the spindle I2 and is adapted to cooperatewith or t a socket 26 in the member 22 to limit the inward or rearwardmovement of the clutch member on the spindle. The clutch members 2| and22 have axially projecting parts 21 on their opposing ends or sides.'I'he parts 21 are adapted to mesh or interlock to connect the spindleI2 with the shaft II for rotation by the shaft. The engaging sides orfaces 25 of the clutch parts 21 are bevelled or pitched so that theytend to slip one on the other when subjected to torque. 'I'he outeredges of the cooperating clutch parts 21 are preferably chamfered orbevelled.

'Ihe clutch Il includes yieldable means for urging the member 22rearwardly or toward the clutch member 2|. A longitudinally adjustablecollar 30 surrounds the spindle I2 and is adapted to be releasablylocked or set in a selected position by a set screw 3| or equivalentmeans. A spring 32 surrounds the spindle I2 and is under compressionbetween the collar 30 and a washer 33 bearing on the outer end of thesleeve portion 23 of the clutch member 22. The spring 32 operates tonormally hold the clutch member 22 in a position where the bottom Wallof its socket 26 engages the head 25. In accordance with the inventionthe shaft II and the spindle l2 are related for limited relativelongitudinal movement whereby the engagement of the clutch parts 21 ofthe clutch members 2| and 22 is accomplished by the operator moving thebody III inwardly when the socket I3 is in engagement with a nut orsecuring member.

The clutch I4 includes a slack connection between the shaft II and thespindle I2 whereby the shaft II may be moved forwardly relative to thespindle I2 to engage the clutch parts 21. The clutch member 22 carries atube or sleeve Il which projects from the active end of the clutchmember to surround the clutch member 2 I. The sleeve 3l may be threadedor otherwise attached to the periphery of the member 22. vAn inwardlyprojecting annular flange 35 is provided on the inner end of the sleeve34 and is adapted to engage the inner or rear surface of the clutchmember 2| to limit the relative axial movement between the shaft Il andthe spindle I2 in one direction. The forward faces of the clutch parts21 on the member 2| are adapted to engage the face of the head 25 tolimit the relative longitudinal movement betweenthe shaft I'I and thespindle .I2 in the other direction.` The sleeve 3l and its ange 35 mayhave sliding bearing cooperation .with the clutch member 2| to assist incarrying and steadying the spindle |2.

A reduced stem 36 projects rearwardly from the head 25 and is slidablein a central socket 31 inthe shaft II. A spring 3B is arranged undercompression between opposing parts or faces on the shaft I I and thespindle I2 to normally yieldingly hold the spindle in an yout positionwhere the clutch parts 21 are disengaged and the flange The tudinal axisof the tool.

35 engages the rear surface of the member 2|.

In the particular form of the invention shown inv the drawings thespring 38 is arranged in the socket 31 under compression between the endof the stem 36 and the bottom wall of the socket. The spring 38 ispreferably weaker than the spring 32 for the reason to be hereinafterdescribed. The spring 32 normally holds the clutch member 22 in aposition wherev the bottom wall of its socket 26 engages the head 25 andthe spring 38 normally holds the spindle 32 in a position Where theclutch parts 21 are disengaged and the flange 35 engages the rearsurfaceof the clutch part 2I.- When the socket I3 is engaged with a nutor securing member the operator pushes inwardly on the handle I8 tocompress the spring 38 and move the body I0 and the shaft II inwardlyybringing the clutch parts 21 against one another or in meshingengagement. In the event that the clutch parts 21 on the members 2| and22 do not come into mesh the operator -partially turns or rocks thebodyI0 to bring the clutch parts 21 into proper meshing engagement. When theclutch parts 21 are in meshing or interlocking engagement the parts 21of the clutch member 2| cooperate with the parts 21 of the clutch member22 to transmit rotation from the shaft II to the spindle I2.

The control for the motor M is associated with and operated by theclutch I4 to automatically cie-energize the motor M when the clutchIIIreleasesunder torque caused by resistance to rodowny securing memberwith ywhich the socket I3 l is engaged. The motor M is adapted to beenergized or operated by electric current carried by the conductors I9and 28. One lead of the energizing circuit, say the conductor 28, may beconnected to one side or post of the motor M. A conductor 40 extendsfrom the other post of the motor M to a binding post or screw 4I on theforward end of the reduced body part I1. The second conductor or lead I8 of the energizing circuit extends through the body I to a post orscrew 42 on the forward end of the body part I1. The control I includescontacts 43 connected with or carried by the screws 4| and 42. Thecontacts 43 comprise flexible strapsv or members having base flanges 44.The flanges 44 are provided with longitudinal slots 45 receiving thescrews 4I and 42. The screws 4| and 42 secure the contezts in positionwhile the slots 45 allow the contacts to be adjusted toward and awayfrom the longitudinal center of the tool when the screws are loosened.The contacts 43 and the screws 4| and 42 are suitably insulated from thebody part I1 by blocks 9 of insulation. The contacts 43 projectvaxiallyor 'forwardly from their bases 44 and are provided at their outer endswith spherical parts or heads 46. l I

An annular or tubular extension 41 is threaded on thev'inner end of thesleeve 34 and has anl inwardly projecting annular` flange 48. The inner'surface of the flange 48 is bevelled or inclined rearwardly andoutwardly relative to the longi- 'Ihe particular control I5 illustratedincludes a ring contact 5I|which may be rotatably carried between theflange 35` and the ange 48. In the construction shown l ,contact againstrotation. The periphery and sides of the vring contact 58 are providedwith Vinsulation or thesesurfaces of the contact bear on a lining 49 ofsuitable insulation. A groove 5I is provided in the internal wall orside of the ring 58? The groove 5I has spherically concaved walls and isadapted to receive the substantial- Gly spherical heads 46 of thecontacts 43.

contact 50 is, of course, formed of conducting material and constitutesa bridge between the conductors or lines I9 and 40 when it is in theposition where its groove 5I receives the contact heads 46. g Theinsulating lining 48 preferably covers the inclined face of the flange48. The contacts 43 are positioned and formed so that their heads 46vare engaged by the lining 49 on the inclined face 'of the flange 48upon inward movementof the body I0 relative to the spindle I2 and thisengagement results in inward flexing of the contact 43 so that the heads46 snap into the groove 5I and remain in Yproper bearing contact withthe wall of the groove through the outward pressure exerted by theresilient contacts.

The control I5 includes a manual switch 52 connected in one of theenergizing lines or conductors I9 or 2D. Inthe particular caseillustrated in the drawings the switch 52 is provided in the line I9.The switch 52 includes a spring 53 which normally acts to hold theswitch in its open position. The switch 52 includes a handle or trigger54 whereby it may be readily closed by the operator of the wrench. Thetrigger 54 rprojects from the inner side of the portion of the handle I8gripped by the users fingers so that the vuser engaging the handle I8has full control over the switch 52. It will be apparent how the usermay easily depress the trigger| 54 to close the switch 52. The controlI5 may include a second manual switch 55 provided in a line 56 to shuntpast the switch 52. The switch 55 which may or may not be employedislocated for convenient engagement by the operator and is such that itmay be operated to a closed position to remain closed until deliberatelyopened so/that the operation of the wrench may be automatic orcompletely under the'control of the clutch I4. A protective shell 58 maybe secured 4to the re-n duced body portion I1 and may extendjirwardly totelescope over the extension 41 and' thus enclose the space between thebody portion I1 and the extension and protect the contacts 43 and theadjacent parts.

In operation assuming the switch 55 to be open and the socket I3 to bein engagement with a nut or the head of a securing member, the operatorgripping the handle lI8 depresses the trigthe clutch member 2| towardthe clutch member 22 bringing the clutch parts 21 of the two,

members into cooperation.v .In the event that the clutch parts 21 do notmesh or' interlock the operator may partially turn'or rock the'body I0eration. During the inward movement of the body I0 into engagement ofthe clutch parts 21 the heads 46 of the contacts 43 aremoved in- The' .65 bringing the clutch niembers to positions where Y their clutch parts21 come into meshing coopeures the proper engagement of the heads 46 inthe groove 6I. snapping of the contact heads 46 into the groove 5I ofthe bridge contact or ring contact 50 completes the energizing circuitto the motor M so that the motor is automatically energized.

Operation or energization of the motor M of course results in rotationof the shaft II and the parts 21 of the clutch member 2| cooperate withthe parts 21 of the clutch member 22 to transmit rotation from the shaftII to the spindie I2. The operator may maintain a suitable or desirableinward pressure on the handle I8 as the motor operates to turn thespindle I2 and thus tighten down the nut or securing member engaged bythe socket I3. The inward pressure exerted by the spindle on the handleI8 ol' course must be sufficient to overcome the spring 38 and maintainthe clutch member 2| in proper engagement with the clutch member 22. Inpractice the spring 38 may be comparatively light and easily compressed.As the nut or securing member is tightened down it offers increasedresistance to rotation of the spindle I2. Upon the nut or securingmember being tightened down toga definite or predetermined degree oftightness itoflers such resistance to rotation of the spindle I2 thatthe torque imposed on the contacting clutch parts 21 overcomes thefrictional cooperation between their sloping faces 28 and overcomes thepressure exerted by the spring 32 and results in outward movement of theclutch member 22 on the spindle I2. This outward movement of the clutchmember 22 of course disengages the clutch parts 21. Outward movement ofthe clutch member 22 on the spindle I2 caused by the release of theclutch parts 21 moves the ring contact 58 outwardly disengaging it fromthe contact heads 48 breaking or opening the energizing circuit to themotor M. Thus the release of the clutch C causes opening of the motorcircuit and de-energization of the motor. Accordingly, the rotation ofthe shaft I I stops substantially simultaneously with the disengagementof the clutch C .so that the clutch parts are not subjected to excessivewear. As soon as the motor M is automatically de-energized by thedisengagement of the clutch I4 the operator may relieve the pressure onthe trigger'64 to allow the switch 62 to open and may relieve the inwardpressure on the wrench and disengage the` socket I3 from the nut orsecuring member.

From theabove it will be noted that the disengagement or release oftheclutch member 22 -from the clutch' member 2| is entirely automaticand independent of the inward pressure exerted on the wrench by theoperator.` The inward pressure put o n the wrench by the operator is4transmitted from the shaft II to the spindle I2 by the engagement ofthe outer faces of the clutch parts 21 on the clutch member 2I with theface of the head 25. This engagement of the parts 21 with the head 26 inno way affects the disengagement of the clutch I4. As the control I5 isoperated or governed by the clutch I4 to open the motor circuitsimultaneously with the disengagement of the clutch I4 the motor isautomatically cie-energized simultaneously with the opening of theswitch so that no time is lost following the disengagement of theclutch. The wrench may be adjusted or regulated to tighten down thesecuring members te any selected or desired degree of tightness byloosening the set screw 3| and adjusting the collar 30 longitudinally onthe spindle I2. Longitudinal adjustment of the collar 30 of courseadjusts or regulates the pressure exerted on the clutch part 22 by thespring 32 determines the torque under which the clutch I4 releases andthus determines the degree to which the wrench tightens down thesecuring members before the motor M becomes deenergized. If the operatorcloses the switch 56 and leaves it closed during the operation of thewrench, the motor M is governed solely by the control I5. In otherwords, the inward movement of the body I0 relative to the spindle I2when the socket I3 is in engagement witha securing member moves thecontacts 46 into engagement with the ring 56 to automatically energizethe motor M and the release of the clutch I4 as described above resultsin de-energization of the motor M. As the operation of the wrench may beentirely automatic or under the control of the clutch I4 and the controlI5 the operator may leave the switch closed, if desired.

The form of the invention illustrated in Figs. 5 to 8, inclusive, of thedrawings, is in the nature of an attachment for a power tool or wrenchT. The tool T which is typical of wrenches and tools of this classincludes a body 60 enclosing an elec tric motor 6I and a suitable speedreduction gearing (not shown). The reduction gearing is provided in areduced forward portion 62 of the body 60 and the shaft 63 driven by themotor 6I through the gearing projects from the forward end of theforward portion 62. The wrench or tool T further includes a spindle 64carrying a screw driver bit, a socket 65 or other means for engagingscrews, nuts, bolts or the like. A releasable clutch is provided betweenthe shaft 63 and the spindle 64. The clutch comprises two clutch members'66 and 61. The member 66 is integral with .the shaft 63 and the member61 is integral with the spindle 64. Clutch parts 68 are provided on theopposing faces of the members 66 and 61 to mesh or interengage for thetransmission of rotation from the shaft 63 t0 the spindle 64. Theengaging faces or sides 68l of the parts 68 are pitched and tend todisengage` when the sides are under torque. A reduced stem 69 on therear end of the spindle 64 or its clutch member 61 is slidable in acentral socket 10 in the shaft 63. A spring 1I is provided in the socket16 and is under compression between the bottom of the socket and the endof the stem 69 to normally yieldingly urge the spindle 64 to an outposition where the clutch parts 68 are disengaged. A handle 12 isprovided on the rear or outer end of the body 60 to facilitate themanipulation of the tool. The motor 6I is adapted to be manuallycontrolled by a switch 13 connected in one lead 14 of the motor circuit14-15. The switch 13 includes a spring 16 which normally holds it in theopen position and includes a trigger- 11 projecting from the forwardside of the portion of the handle 12 gripped by the operators fingers.The structure of the tool T described above may be considered as typicalof the general class of power tools to which the attachment' of theinvention is applicable.

The attachment provided by the present in? vention illustrated in Figs.5 to 8, inclusive, of the drawings, includes, generally, spaced contacts18 connected in the motor energizing circuit 14--15, a sleeve 19 carriedby the spindle 64 and a ring contact 80 carried by the sleeve 15 andengageable by the contacts 18 to complete the circuit to the motor 6I. Y

The contacts 18 are preferably mounted on or attached to the forward endof the body portion rearwardly from the sleeve.

62 at spaced points. They are shown at diametrically opposite sides ofthe shaft 63. 'I'he contacts 18 may be carried by blocks 8| ofinsulation secured to the body portion 62 in any suitable manner. Thecontacts 18 are flexible straplike members each having a base flange 82seated on an insulation block 8|. Screws 83 threaded into openings inthe blocks 8| pass through slots 84 in the flanges 82 to adjustablyattach the contacts 18 to the blocks. When the screws 83 are loosenedthe contacts 18 may be adjusted toward and away from the longitudinalaxis of the tool T. The contacts 18 project outwardly from their baseflanges 82 and are provided at their outer ends with spherical heads 85.The leads or conductors 14 and 15 of the motor energizing circuit may beelectrically connected with the contacts 18 in any suitable manner. Inthe particular case illustrated in the drawings the conductors 14 and15.are wrapped on or soldered to the screws 83 to be electricallyconnected with the contacts 18. `The conductors 14 and 15 are preferablytrained over the exterior of the tool body 68 and its reduced forwardportion 62 to the conductors 18 so that it is unnecessary to disturb theinterior of the tool to provide for the arrangement of theconductorsf'on the tool. y

The sleeve 19 is provided to carry or support ,the ring contact 88. Thesleeve 19 replaces the means originally provided on the tool T forconnecting the spindle 64 with the shaft 63 for longitudinal movementrelative to the shaft. In accordance with the invention the sleeve 19 issecured to the clutch member 61 of the spindle 64. The sleeve 19surrounds the member 61 and projects rearwardly therefrom to surroundand slidably engage the periphery of the clutch member 66. The sleeve'|'9 may be fixed to the clutch member 61 in any suitable manner, forexample, it may be welded to the member 61 as at 86. An inwardlyprojecting annular ange 81 isv provided on the rear end of the sleeve 19and is adapted to engage the rear face of the clutch member 66 to limitrelative longitudinal movement between the shaft 61 and the spindle 64in one direction. An extension 88 is threaded on the rear end portion ofthe sleeve 19 to project y The extension 88 has an inwardly projectingannular flange 89 spaced from theiiange 81 to leave or provide anannular groove 98. The internal surface 9| of the flange 89 is inclinedoutwardly and rearwardly as clearly illustrated in Figs. 5 and 8 of thedrawings.V A'protective sheath or shell 99 may be providedv on thereduced portion 62 ofthe tool body 68 to extend-forwardly and telescopeover the extension 88 of the sleeve 19 and thus enclose orsurround thespace between the extension andl theforwardend of the-body.

The ring contact 88 is engageableby the contacts 18 when there is inwardmovement of the orffreeto float in the groove 90. 'Ihe groove 98 alining 92 of insulation to prevent engageme'niof the Contact so with themange a1 or the vextexrsiox'i 88. 'Ihe lining 92'of insulationcontlnp'es rearwardly to extend over and cover the inclinedsurface .9|of the flange 89 so that the heads .85 of the contacts 18 cannot engagethe surface 9| simultaneously with their engagement with theiringcontact 88. An annular groove 93 is provided in the interior or internalsurface of the ring contact 88. The groove 93 has a spherically concavedwall and is proportioned to effectively receive the spherical heads 85of the contacts 18.

If desired or found practical a manual switch 94 may be connected in aline 15 to shunt out the switch 13. The switch 94 is such that it mayremain in either the open or closed condition until deliberately shiftedor operated by the user of the tool. The switch 84 may be an originalelement ofthe tool T or may be applied to the tool when the attachmentis embodied in the tool.

It is believed that it will be apparent how the contacts 18 may beeasily and quickly attached to the forward end of the body portion 62and properly connected in the motor circuit. The sleeve 91 carrying theextension 88 the contact ring 88 and the shell 9|.may be easily andquickly attached to the clutch member 69. The attachment of theinvention is such that it may be readily applied to or embodied in thepower tool with very little alteration or modification of the originaltool structure. Y

-In the operation of the tool T provided with the attachment theoperator may prefer to have the switch 94 in its open condition in whichcase he iirst engages the socket 65 with the nut, bolt or'other securingmember and then moves or pushes the tool body 68 inwardly. This inwardmovement may be accomplished by engaging or grasping the handle 12 Vandpushing inwardly thereon. As the operator moves the tool body 68inwardly he may depress the trigger 11 to close the switch 13. Theengagement of the socket 65 withthe securing member or the workholds-the spindle 64 against inward or longitudinal movement and as thetool' body 68 is moved inwardly the heads 85 ofthe contacts 18 engagethe lining of insulationon the inclined surface 9| and the contacts areflexed inwardly so that their heads 85 may snap into the groove 93 ofthe contact ring 88. The resiliency of the contacts 98 holds their heads85 in proper engagement with the wall of the groove 93. The engagementof the contact tially simultaneously with the energizaton of-theRotation of the spindle 64 by the motorl 6| driving through the shaft 63and the clutch causes the nut, bolt or other. securing member to beturned down or tightened. When the securing member has been tightened toa suitable degree of tightness the yinclined cooperating faces 68il ofthe contact parts 68 slip and disengage under the increased torquecausing the shaft 63 and the tool body 58 to move or kick rearwardly.This movement of the shaft 63 and the tool body 68 of course releasesthe clutch and is accompanied b y disengagement of the contact heads 85from the contact ring 88 so that the motor y6| is deenergizedsubstantially simultaneously with the disengagement or release oftheclutch. Thus the motor of the power Atool T is automatically deenergizedwhen the nut or securing member has been tightened to the desired degreeof tightness so that the clutch parts 68 are not subjected to excessiveunnecessary wear and no time is lost in the operation of the tool.erator may have the switch 95 in a closed condition during the operationof the tool. When the switch 94 is closed the tool may be operatedautomatically or without the depression oi the trigger 11. With theswitch 9! in the closed condition the engagement of the contact heads 85with the contact ring 80 results in closing of the motor circuitregardless of the condition oi the switch 13 so that the tool isautomatically energized or actuated by the inward movement of the toolbody 80. The contacts 1l may be adjusted radially to insure the properengagement of their heads 85 with the ring contact 80.

Having described only typical preferred forms and applications of myinvention I do not wish to be limited or restricted to the specificdetails set forth, but wish to reserve to'myselt any variations ormodiilcations that may appear to those skilled in the art or fall withinthe scope of the following claims.

Having described my invention, I claim:

1. In a portable power tool having a driving motor and an energizingcircuit for the motor, the combination of a driving element driven bythe motor, a driven element, a clutch comprising clutch members on theelements, the clutch members being related for relative movement between an engaged rotation transmitting position and a released positionand being formed to move one relative to the other to said releasedposition when subjected to a heavy torque, and means normally yieldinglyholding the clutch members in the released position, and a control forthe motor governed by movement between the clutch members includingcooperable contacts movable axially with the clutch members.

2. In a portable power tool having an energiz# ing circuit,- thecombination of a driving element, a driven element, a clutch comprisingclutch members on the elements, the clutch members being related forrelative movement between an engaged rotation transmitting position anda released position and being formed to move one relative to the otherto said released position when subjected to a heavy torque, and acontrol for the energizing circuit including contacts in said circuit,one of the contacts being movable axially with one clutch member, theother contact being movable axially with the other clutch member, thecontacts being engaged when the clutch members are in the engagedposition and disengaged when the clutch members are in the releasedposition.

3. In a portable power tool having an energizing circuit. thecombination o! a driving element, a driven element. a clutch comprisingclutch members on the elements, the clutch members being related forrelative movement between an engaged rotation transmitting position anda released position and being Lormed to move one 'relative to the otherto said releasedposition whim subjected to a heavy torque. a springnormally yieldingly holding the clutch members in the released podtion,rand a control for the energizing circuit including a contact in thecircuit associated with one element to be movable axially therewith, anda contact in the circuit movable axially with the clutch member on theother element, the contacts being disengaged to open said circuit uponmovement o! the clutch members to the released pomtion.

-4. In a power tool a motor, an energizing circuit for the motor, adriving element operated by the motor a driven element, clutch memberson If desired, the opthe elements, the clutch members being related forrelative movement between engaged rotation transmitting positions andreleased positions, parts on the clutch members cooperable when themembers are in the engaged positions and shaped to cause relativemovement of the members to the released .positions when substantialresistance is offered to rotation of the driven element, and contactmeans operable to open said circuit when the clutch members are-movedone relative to the other to the released positions, said meansincluding a contact in said circuit movable axially with one clutchmember, and a contact in said circuit movable axially with and rotatablycarried by the other clutch member for cooperation with the firstmentioned contact.

5. In a portable power tool having a motor and an energizing circuit forthe motor, `the combination of, a driving element driven by the motor, adriven element, the elements being related for relative axial movement,clutch members on the elements, the clutch members being related forrelative movement between engaged rotation transmitting positions andreleased positions, parts on the clutch members cooperable when themembers are in the engaged positions and shaped to cause relativemovement of the members to the released positions when substantialresistance is oiered to rotation of the driven element, means normallyyieldingly holding the clutch members in the released position, and acontrol for said circuit including contacts connected in the circuit andassociated with the elements and the clutch members to come intoengagement to energize the motor when the elements are shifted axiallyone relative to the other v to engage the clutch members and todisengage to deenergi'ze the motor when the clutch members are released.

6. In a power tool having a motor and an energizing circuit for themotor, the combination of a driving element driven by the motor, adriven element, clutch members on the elements, the clutch members beingrelated for relative movement between engaged rotation transmittingpositions and released positions, parts on the clutch members cooperablewhen the members are in the engaged positions and shaped to causerelative movement of the members to the released positions whensubstantial resistance is offered to rotation of the driven element, anda control for said circuit including spaced contacts each connected witha lead of said circuit and mounted to move longitudinally with one oithe clutch members. and a contact mounted to move longitudinally withthe other clutch member and cooperable with the spaced contacts when theclutch members are engaged and disengaged irom the spaced contacts whenthe clutch members are released.

7. In a powertool having a motor and an energizing circuit for themotor, the combination of a driving element driven by the motor, adriven element, clutch members on the elements, the clutch members beingrelated for relative movement between engaged rotation transmittingpositions and released positions, parts on the clutch members cooperablewhen the members are in the engaged positions and shaped to causerelative movement oi the members to the released positions when the partengaged by the socket offers substantial resistance to rotation, and acontrol for said circuit including spaced contacts each connected with alead of said circuit and mounted to move longitudinally with one of theclutch members, 'and a rotatable ring contact mounted to movelongitudinally with the other clutch member and cooperable with thespaced contacts when the clutch members are engaged and disengaged fromthe spaced contacts when the clutch members are released.

8. In a portable power tool having a driving motor, an energizingcircuit'for the motor, a driving element driven by the motor, a drivenelement shiftable relative to the driving element, and cooperable clutchmembers on the elements releasable under torque to cause relativelongitudinal movement between the elements, the combination of spacedcontacts connected in the circuit and mounted to move 1ongitudina11ywith mel release.

9. In a portable power tool having a driving motor, an energizingcircuit for the motor, a driving element driven by the motor, a drivenelement shiftable relative to the driving element,.

and cooperable clutch members on the elements releasable under torquetocause relative longitudinal movement between the elements, thecombination of spaced contacts connected in the circuit and mounted onthe driving element to move longitudinally with the driving element, asleeve carried by the driven element, and a contact rotatably carried bythe sleeve and cooperable with the spaced contacts to complete the motorcircuit when the clutch members are engaged and, disengageable from thespaced contacts to open the motor circuit when the clutch membersrelease.

v10. An attachment for a power tool having a driving motor, a circuitfor energizing the motor, a shaft driven by the motor, a tool spindle,the shaft and spindle being related for relative longitudinal movementand cooperable clutch -members xed on the shaft and spindle releasable'under torque to cause relative longitudinal movement between the shaftand spindle,the attachment including a contact adapted to be mounted onthe tool to be movable longitudinally with the shaft, means for mountingsaid contact on the tool free of the shaft the contact being connectedin said circuit, and a contact .adapted to be mounted on the spindle tomove longitudinally.= therewith and cooperable with the iirst mentionedcontact when the clutch members are engaged and disengageable from thefirst mentioned contact to open the motor circuit when the clutchmembers release.

11. An attachment for a power tool having a ldriving motor, a circuitfor energizing the motor, a shaft driven by the motor, a toolspindle,

Athe shaft and spindle being related for relative members are engagedand disengageable fromthe rst mentioned contact to open the circuit whenthe members release.

12. An attachment for a power tool having a driving motor, a circuit forenergizing the motor, a shaft driven by the motor, a tool spindle,

the shaft and spindle being related or relative longitudinal movementand cooperable clutch members fixed on the shaft and spindle releasableunder torque to cause relative longitudinal movement between the shaftand spindle, the attachment includingl a contact adapted to be mountedon the tool to be movable longitudinally with the shaft, the contactbeing connected in said circuit, asleeve adapted to be attached to theclutch member on the spindle, and a ring contact rotatable in the sleeveand having a groove for receiving the first mentioned contact to'closethe circuit when the members are engaged, the ring contact beingdisengageable from the iirst mentioned contact to open the circuit whenthe members release.

13. A portable'power tool includingy a body, a motor carried by thebody, a circuit for actuating the motor, two rotatable elements relatedfor relative longitudinal movement, one element being a driving elementdriven vby the motor, the other element being a driven element, clutchmembers on the elements engageable upon relative longitudinal movementbetween the elements to connect the elements for rotation, meansnormally yieldingly holding theyclutch member out of engagement, acontrol for the circuit includingtwo contacts one being movablelongitudinally with each clutch member, the contacts being cooperablewhen the clutch members`are engaged t0 4complete the circuit, oneclutch. member being longitudinally shiftable on its element, and en--gaging parts on the clutch members operable to cause longitudinalshifting of the shiftable member to disengage the contacts when there isheavy Y resistance to rotation'of the driven element.

14. In a portable power tool having a body, a motor carried by the bodyand a circuit for actuating the motor, the combination of two rotatableelements related for relative longitudinal movement, one element being ashaft driving element driven by the motor, the other element being adriven element, clutch membersv on the elements engageable uponlrelative longitudinal movement between-theA elements to connect theelements forrotation, means normally yieldingly holding the clutchmembers out of engagement, a control for the circuit including twocontacts one being movable longitudinally with each clutch member, thevcontacts being cooperable when the clutch members are engaged tocomplete the circuit, one

clutch member being longitudinally shiftable on its f element, meansnormally yieldingly resisting longitudinal shifting of the shiftablemember, and engaging parts on the. clutch members operable to causelongitudinal shifting of the shiftable member to disengage the contactswhen there is heavy resistance to rotation of the driven element.

15. In a portable power tool of the character described having a motorand a circuit fortactuating the motor, the combination of two rotatableelernents related for relative longitudinal movement, one being adriving element driven by the motor, the other being a driven element,clutch members on the elements engageable upon relative longitudinalmovement between the elements to connect the elements for rotation,means normally yieldingly holding the clutch members dismeans, a contactmovable longitudinally with each element, the contacts being cooperablewhen the clutch members are engaged to complete the circuit, and partson the clutch members operable to cause longitudinal shifting of saidmember when under torque to disengage the contacts.

' 16. A portable power tool including a body, a motor carried by thebody, a circuit for actuating the motor, two rotatable elements relatedfor relative longitudinal movement, one being a driving element drivenby the motor and movable longitudinally with the body, the other being adriven element movable axially relative to the body, clutch members onthe elements engageable upon relative longitudinal movement between theelements to connect the elements for rotation. means normally yieldinglyholding the clutch members out of engagement, one of the clutch membersbeing axially shiftable on its element, a contact mounted to movelongitudinally with one element, a contact carried by the axiallyshiftable member. the contacts cooperating when the clutch members areengaged to complete said circuit, and cooperating parts on the clutchmembers operable to cause axial shifting of said members to disengagethe members and the contacts when a heavy torque is imposed on themembers.

17. A portable power tool including a body, a motor carried by the body,a circuit for actuating the motor, two rotatable elements related forrelative longitudinal movement, one being a driving element driven bythe motor, the other being a driven element shii'table axially relativeto the body, clutch members on the elements engageable upon relativelongitudinal movement between the elements to connect the elements forrotation, means normally yieldingly holding the clutch members out ofengagement, one of the clutch members being axially shiftable on itselement, a contact mounted to move longitudinally with one element, aspring bearing on the axially shiftable member to resist its axialmovement, a contact carried by the axially shiftable member, thecontacts cooperating when the clutch members are engaged to completesaid circuit, and cooperating parts on the clutch members operable tocause axial shifting of said members to disengage the members and thecontacts when a heavy torque is impod on the members.

18. A portable power tool including a body, a motor carried by the body,a circuit for actuating the motor, two rotatable elements related forrelative longitudinal movement, one being a driving element driven bythe motor, the other being a tool driven element shiftable axiallyrelative to the body, clutch members on the elements engageable uponrelative longitudinal movement between the elements to connect theelements for rotation, means normally yieldingly holding the clutchmembers out of engagement, one of the clutch members being axiallyshiftable on its element, a contact mounted to move longitudinally withone element, a spring bearing on the axially shiftable member to resistits axial movement, means for regulating the pressure exerted by thespring, a contact carried by the axially shiftable member, the contactscooperating when the clutch members are engaged to complete saidcircuit, and cooperating parts on the clutch members operable to causeaxial shifting of said members to disengage the members and the contactswhen a heavy torque is imposed on the members.

19. In a portable power tool having a driving motor and an energizingVcircuit for the motor, the combination of, a driving element driven bythe motor, a driven element, a clutch comprising, clutch members on theelements related for relative movement between an engaged position and areleased position and being formed to move relative to one another tothe released position when subjected to heavy torque, a control i'or themotor circuit governed by movement between the clutch members, and anoptional manual switch in said circuit. a

20. In a portable power tool having a driving motor and an energizingcircuit for the motor, the combination ol', a driving element driven bythe motor, a driven element, a clutch comprising, clutch members on theelements related for relative movement between an engaged position and areleased position and being formed to move relative to one another -tothe released position when subjected to heavy torque, contact means insaid circuit associated with the clutch members to automatically controlsaid circuit, and a manual switch for controlling said circuit at theroption of the operator.

WALTER HALL.

